Career Development Plan: I am requesting five years of funding through a Mentored Patient-Oriented Research Career Development Award in AIDS Research (PA-03-086) in order to develop as an independent researcher investigating neuropsychiatric and neurophysiologic features of HIV/HCV coinfection. My overall goals are 1) to learn about HIV/HCV coinfection and its impact on the brain and 2) to implement a research project investigating cognitive, psychiatric, and neurophysiologic features of HIV/HCV coinfection. My ultimate career goal is to become an independent investigator of the neuropsychiatric features of comorbidities in neuroAIDS. Career Development Plan: A comprehensive program is proposed that includes a didactic curriculum, tutorials in magnetic resonance spectroscopy imaging (MRSI), neurobiology of HIV, HIV/HCV coinfection, and neuropsychiatric research methods. Background of Proposed Research Project: HIV/HCV coinfection is an emerging, significant comorbidity in neuroAIDS. To date, the neurobehavioral consequences of HIV/HCV coinfection have not been fully characterized although each virus has been shown to independently cause neuropsychiatric disturbance. Research Project Aims: To determine whether a differential effect of HCV viremia can be detected in brain via neurometabolites and in behavior via neuropsychologic deficits among HIV/HCV coinfected, HCV-only, and HIV-only monoinfected patients. Methods: One hundred HIV/HCV coinfected patients with and without HCV viremia as well as 50 HIV-only and 50 HCV-only patients will receive a MRSI, a psychiatric interview, and a neuropsychologic assessment. The study will test the hypothesis that HCV viremia is associated with increased choline, increased myo-inositol, and increased GIx as well as executive functioning deficits. Significance: This study will identify neuropsychiatric and neurophysiologic features of HCV viremia in HIV/HCV coinfection and will serve as a template for neuropsychiatric research of comorbidities in neuroAIDS.